import {
  AnimationClip,
  Bone,
  Box3,
  BufferAttribute,
  BufferGeometry,
  ClampToEdgeWrapping,
  Color,
  DirectionalLight,
  DoubleSide,
  FileLoader,
  FrontSide,
  Group,
  ImageBitmapLoader,
  InterleavedBuffer,
  InterleavedBufferAttribute,
  Interpolant,
  InterpolateDiscrete,
  InterpolateLinear,
  Line,
  LinearFilter,
  LinearMipmapLinearFilter,
  LinearMipmapNearestFilter,
  LineBasicMaterial,
  LineLoop,
  LineSegments,
  Loader,
  LoaderUtils,
  Material,
  MathUtils,
  Matrix4,
  Mesh,
  MeshBasicMaterial,
  MeshPhysicalMaterial,
  MeshStandardMaterial,
  MirroredRepeatWrapping,
  NearestFilter,
  NearestMipmapLinearFilter,
  NearestMipmapNearestFilter,
  NumberKeyframeTrack,
  Object3D,
  OrthographicCamera,
  PerspectiveCamera,
  PointLight,
  Points,
  PointsMaterial,
  PropertyBinding,
  Quaternion,
  QuaternionKeyframeTrack,
  RepeatWrapping,
  RGBFormat,
  Skeleton,
  SkinnedMesh,
  Sphere,
  SpotLight,
  sRGBEncoding,
  TangentSpaceNormalMap,
  Texture,
  TextureLoader,
  TriangleFanDrawMode,
  TriangleStripDrawMode,
  Vector2,
  Vector3,
  VectorKeyframeTrack
} from '../../three.module.js';

class GLTFLoader extends Loader {

  constructor(manager) {

    super(manager);

    this.dracoLoader = null;
    this.ktx2Loader = null;
    this.meshoptDecoder = null;

    this.pluginCallbacks = [];

    this.register(function (parser) {

      return new GLTFMaterialsClearcoatExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFTextureBasisUExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFTextureWebPExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFMaterialsSheenExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFMaterialsTransmissionExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFMaterialsVolumeExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFMaterialsIorExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFMaterialsSpecularExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFLightsExtension(parser);

    });

    this.register(function (parser) {

      return new GLTFMeshoptCompression(parser);

    });

  }

  load(url, onLoad, onProgress, onError) {

    const scope = this;

    let resourcePath;

    if (this.resourcePath !== '') {

      resourcePath = this.resourcePath;

    } else if (this.path !== '') {

      resourcePath = this.path;

    } else {

      resourcePath = LoaderUtils.extractUrlBase(url);

    }

    // Tells the LoadingManager to track an extra item, which resolves after
    // the model is fully loaded. This means the count of items loaded will
    // be incorrect, but ensures manager.onLoad() does not fire early.
    this.manager.itemStart(url);

    const _onError = function (e) {

      if (onError) {

        onError(e);

      } else {

        console.error(e);

      }

      scope.manager.itemError(url);
      scope.manager.itemEnd(url);

    };

    const loader = new FileLoader(this.manager);

    loader.setPath(this.path);
    loader.setResponseType('arraybuffer');
    loader.setRequestHeader(this.requestHeader);
    loader.setWithCredentials(this.withCredentials);

    loader.load(url, function (data) {

      try {

        scope.parse(data, resourcePath, function (gltf) {

          onLoad(gltf);

          scope.manager.itemEnd(url);

        }, _onError);

      } catch (e) {

        _onError(e);

      }

    }, onProgress, _onError);

  }

  setDRACOLoader(dracoLoader) {

    this.dracoLoader = dracoLoader;
    return this;

  }

  setDDSLoader() {

    throw new Error(
      'THREE.GLTFLoader: "MSFT_texture_dds" no longer supported. Please update to "KHR_texture_basisu".'
    );

  }

  setKTX2Loader(ktx2Loader) {

    this.ktx2Loader = ktx2Loader;
    return this;

  }

  setMeshoptDecoder(meshoptDecoder) {

    this.meshoptDecoder = meshoptDecoder;
    return this;

  }

  register(callback) {

    if (this.pluginCallbacks.indexOf(callback) === -1) {

      this.pluginCallbacks.push(callback);

    }

    return this;

  }

  unregister(callback) {

    if (this.pluginCallbacks.indexOf(callback) !== -1) {

      this.pluginCallbacks.splice(this.pluginCallbacks.indexOf(callback), 1);

    }

    return this;

  }

  parse(data, path, onLoad, onError) {

    let content;
    const extensions = {};
    const plugins = {};

    if (typeof data === 'string') {

      content = data;

    } else {

      const magic = LoaderUtils.decodeText(new Uint8Array(data, 0, 4));

      if (magic === BINARY_EXTENSION_HEADER_MAGIC) {

        try {

          extensions[EXTENSIONS.KHR_BINARY_GLTF] = new GLTFBinaryExtension(data);

        } catch (error) {

          if (onError) onError(error);
          return;

        }

        content = extensions[EXTENSIONS.KHR_BINARY_GLTF].content;

      } else {

        content = LoaderUtils.decodeText(new Uint8Array(data));

      }

    }

    const json = JSON.parse(content);

    if (json.asset === undefined || json.asset.version[0] < 2) {

      if (onError) onError(new Error('THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported.'));
      return;

    }

    const parser = new GLTFParser(json, {

      path: path || this.resourcePath || '',
      crossOrigin: this.crossOrigin,
      requestHeader: this.requestHeader,
      manager: this.manager,
      ktx2Loader: this.ktx2Loader,
      meshoptDecoder: this.meshoptDecoder

    });

    parser.fileLoader.setRequestHeader(this.requestHeader);

    for (let i = 0; i < this.pluginCallbacks.length; i++) {

      const plugin = this.pluginCallbacks[i](parser);
      plugins[plugin.name] = plugin;

      // Workaround to avoid determining as unknown extension
      // in addUnknownExtensionsToUserData().
      // Remove this workaround if we move all the existing
      // extension handlers to plugin system
      extensions[plugin.name] = true;

    }

    if (json.extensionsUsed) {

      for (let i = 0; i < json.extensionsUsed.length; ++i) {

        const extensionName = json.extensionsUsed[i];
        const extensionsRequired = json.extensionsRequired || [];

        switch (extensionName) {

          case EXTENSIONS.KHR_MATERIALS_UNLIT:
            extensions[extensionName] = new GLTFMaterialsUnlitExtension();
            break;

          case EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS:
            extensions[extensionName] = new GLTFMaterialsPbrSpecularGlossinessExtension();
            break;

          case EXTENSIONS.KHR_DRACO_MESH_COMPRESSION:
            extensions[extensionName] = new GLTFDracoMeshCompressionExtension(json, this.dracoLoader);
            break;

          case EXTENSIONS.KHR_TEXTURE_TRANSFORM:
            extensions[extensionName] = new GLTFTextureTransformExtension();
            break;

          case EXTENSIONS.KHR_MESH_QUANTIZATION:
            extensions[extensionName] = new GLTFMeshQuantizationExtension();
            break;

          default:

            if (extensionsRequired.indexOf(extensionName) >= 0 && plugins[extensionName] === undefined) {

              console.warn('THREE.GLTFLoader: Unknown extension "' + extensionName + '".');

            }

        }

      }

    }

    parser.setExtensions(extensions);
    parser.setPlugins(plugins);
    parser.parse(onLoad, onError);

  }

  parseAsync(data, path) {

    const scope = this;

    return new Promise(function (resolve, reject) {

      scope.parse(data, path, resolve, reject);

    });

  }

}

/* GLTFREGISTRY */

function GLTFRegistry() {

  let objects = {};

  return {

    get: function (key) {

      return objects[key];

    },

    add: function (key, object) {

      objects[key] = object;

    },

    remove: function (key) {

      delete objects[key];

    },

    removeAll: function () {

      objects = {};

    }

  };

}

/*********************************/
/********** EXTENSIONS ***********/
/*********************************/

const EXTENSIONS = {
  KHR_BINARY_GLTF: 'KHR_binary_glTF',
  KHR_DRACO_MESH_COMPRESSION: 'KHR_draco_mesh_compression',
  KHR_LIGHTS_PUNCTUAL: 'KHR_lights_punctual',
  KHR_MATERIALS_CLEARCOAT: 'KHR_materials_clearcoat',
  KHR_MATERIALS_IOR: 'KHR_materials_ior',
  KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
  KHR_MATERIALS_SHEEN: 'KHR_materials_sheen',
  KHR_MATERIALS_SPECULAR: 'KHR_materials_specular',
  KHR_MATERIALS_TRANSMISSION: 'KHR_materials_transmission',
  KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
  KHR_MATERIALS_VOLUME: 'KHR_materials_volume',
  KHR_TEXTURE_BASISU: 'KHR_texture_basisu',
  KHR_TEXTURE_TRANSFORM: 'KHR_texture_transform',
  KHR_MESH_QUANTIZATION: 'KHR_mesh_quantization',
  EXT_TEXTURE_WEBP: 'EXT_texture_webp',
  EXT_MESHOPT_COMPRESSION: 'EXT_meshopt_compression'
};

/**
 * Punctual Lights Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
 */
class GLTFLightsExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;

    // Object3D instance caches
    this.cache = {refs: {}, uses: {}};

  }

  _markDefs() {

    const parser = this.parser;
    const nodeDefs = this.parser.json.nodes || [];

    for (let nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex++) {

      const nodeDef = nodeDefs[nodeIndex];

      if (nodeDef.extensions
        && nodeDef.extensions[this.name]
        && nodeDef.extensions[this.name].light !== undefined) {

        parser._addNodeRef(this.cache, nodeDef.extensions[this.name].light);

      }

    }

  }

  _loadLight(lightIndex) {

    const parser = this.parser;
    const cacheKey = 'light:' + lightIndex;
    let dependency = parser.cache.get(cacheKey);

    if (dependency) return dependency;

    const json = parser.json;
    const extensions = (json.extensions && json.extensions[this.name]) || {};
    const lightDefs = extensions.lights || [];
    const lightDef = lightDefs[lightIndex];
    let lightNode;

    const color = new Color(0xffffff);

    if (lightDef.color !== undefined) color.fromArray(lightDef.color);

    const range = lightDef.range !== undefined ? lightDef.range : 0;

    switch (lightDef.type) {

      case 'directional':
        lightNode = new DirectionalLight(color);
        lightNode.target.position.set(0, 0, -1);
        lightNode.add(lightNode.target);
        break;

      case 'point':
        lightNode = new PointLight(color);
        lightNode.distance = range;
        break;

      case 'spot':
        lightNode = new SpotLight(color);
        lightNode.distance = range;
        // Handle spotlight properties.
        lightDef.spot = lightDef.spot || {};
        lightDef.spot.innerConeAngle = lightDef.spot.innerConeAngle !== undefined ? lightDef.spot.innerConeAngle : 0;
        lightDef.spot.outerConeAngle = lightDef.spot.outerConeAngle !== undefined ? lightDef.spot.outerConeAngle : Math.PI / 4.0;
        lightNode.angle = lightDef.spot.outerConeAngle;
        lightNode.penumbra = 1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
        lightNode.target.position.set(0, 0, -1);
        lightNode.add(lightNode.target);
        break;

      default:
        throw new Error('THREE.GLTFLoader: Unexpected light type: ' + lightDef.type);

    }

    // Some lights (e.g. spot) default to a position other than the origin. Reset the position
    // here, because node-level parsing will only override position if explicitly specified.
    lightNode.position.set(0, 0, 0);

    lightNode.decay = 2;

    if (lightDef.intensity !== undefined) lightNode.intensity = lightDef.intensity;

    lightNode.name = parser.createUniqueName(lightDef.name || ('light_' + lightIndex));

    dependency = Promise.resolve(lightNode);

    parser.cache.add(cacheKey, dependency);

    return dependency;

  }

  createNodeAttachment(nodeIndex) {

    const self = this;
    const parser = this.parser;
    const json = parser.json;
    const nodeDef = json.nodes[nodeIndex];
    const lightDef = (nodeDef.extensions && nodeDef.extensions[this.name]) || {};
    const lightIndex = lightDef.light;

    if (lightIndex === undefined) return null;

    return this._loadLight(lightIndex).then(function (light) {

      return parser._getNodeRef(self.cache, lightIndex, light);

    });

  }

}

/**
 * Unlit Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
 */
class GLTFMaterialsUnlitExtension {

  constructor() {

    this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;

  }

  getMaterialType() {

    return MeshBasicMaterial;

  }

  extendParams(materialParams, materialDef, parser) {

    const pending = [];

    materialParams.color = new Color(1.0, 1.0, 1.0);
    materialParams.opacity = 1.0;

    const metallicRoughness = materialDef.pbrMetallicRoughness;

    if (metallicRoughness) {

      if (Array.isArray(metallicRoughness.baseColorFactor)) {

        const array = metallicRoughness.baseColorFactor;

        materialParams.color.fromArray(array);
        materialParams.opacity = array[3];

      }

      if (metallicRoughness.baseColorTexture !== undefined) {

        pending.push(parser.assignTexture(materialParams, 'map', metallicRoughness.baseColorTexture));

      }

    }

    return Promise.all(pending);

  }

}

/**
 * Clearcoat Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
 */
class GLTFMaterialsClearcoatExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;

  }

  getMaterialType(materialIndex) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) return null;

    return MeshPhysicalMaterial;

  }

  extendMaterialParams(materialIndex, materialParams) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {

      return Promise.resolve();

    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    if (extension.clearcoatFactor !== undefined) {

      materialParams.clearcoat = extension.clearcoatFactor;

    }

    if (extension.clearcoatTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'clearcoatMap', extension.clearcoatTexture));

    }

    if (extension.clearcoatRoughnessFactor !== undefined) {

      materialParams.clearcoatRoughness = extension.clearcoatRoughnessFactor;

    }

    if (extension.clearcoatRoughnessTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'clearcoatRoughnessMap', extension.clearcoatRoughnessTexture));

    }

    if (extension.clearcoatNormalTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'clearcoatNormalMap', extension.clearcoatNormalTexture));

      if (extension.clearcoatNormalTexture.scale !== undefined) {

        const scale = extension.clearcoatNormalTexture.scale;

        materialParams.clearcoatNormalScale = new Vector2(scale, scale);

      }

    }

    return Promise.all(pending);

  }

}

/**
 * Sheen Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_sheen
 */
class GLTFMaterialsSheenExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_SHEEN;

  }

  getMaterialType(materialIndex) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) return null;

    return MeshPhysicalMaterial;

  }

  extendMaterialParams(materialIndex, materialParams) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {

      return Promise.resolve();

    }

    const pending = [];

    materialParams.sheenColor = new Color(0, 0, 0);
    materialParams.sheenRoughness = 0;
    materialParams.sheen = 1;

    const extension = materialDef.extensions[this.name];

    if (extension.sheenColorFactor !== undefined) {

      materialParams.sheenColor.fromArray(extension.sheenColorFactor);

    }

    if (extension.sheenRoughnessFactor !== undefined) {

      materialParams.sheenRoughness = extension.sheenRoughnessFactor;

    }

    if (extension.sheenColorTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'sheenColorMap', extension.sheenColorTexture));

    }

    if (extension.sheenRoughnessTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'sheenRoughnessMap', extension.sheenRoughnessTexture));

    }

    return Promise.all(pending);

  }

}

/**
 * Transmission Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_transmission
 * Draft: https://github.com/KhronosGroup/glTF/pull/1698
 */
class GLTFMaterialsTransmissionExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_TRANSMISSION;

  }

  getMaterialType(materialIndex) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) return null;

    return MeshPhysicalMaterial;

  }

  extendMaterialParams(materialIndex, materialParams) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {

      return Promise.resolve();

    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    if (extension.transmissionFactor !== undefined) {

      materialParams.transmission = extension.transmissionFactor;

    }

    if (extension.transmissionTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'transmissionMap', extension.transmissionTexture));

    }

    return Promise.all(pending);

  }

}

/**
 * Materials Volume Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_volume
 */
class GLTFMaterialsVolumeExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_VOLUME;

  }

  getMaterialType(materialIndex) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) return null;

    return MeshPhysicalMaterial;

  }

  extendMaterialParams(materialIndex, materialParams) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {

      return Promise.resolve();

    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    materialParams.thickness = extension.thicknessFactor !== undefined ? extension.thicknessFactor : 0;

    if (extension.thicknessTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'thicknessMap', extension.thicknessTexture));

    }

    materialParams.attenuationDistance = extension.attenuationDistance || 0;

    const colorArray = extension.attenuationColor || [1, 1, 1];
    materialParams.attenuationColor = new Color(colorArray[0], colorArray[1], colorArray[2]);

    return Promise.all(pending);

  }

}

/**
 * Materials ior Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_ior
 */
class GLTFMaterialsIorExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_IOR;

  }

  getMaterialType(materialIndex) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) return null;

    return MeshPhysicalMaterial;

  }

  extendMaterialParams(materialIndex, materialParams) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {

      return Promise.resolve();

    }

    const extension = materialDef.extensions[this.name];

    materialParams.ior = extension.ior !== undefined ? extension.ior : 1.5;

    return Promise.resolve();

  }

}

/**
 * Materials specular Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_specular
 */
class GLTFMaterialsSpecularExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_SPECULAR;

  }

  getMaterialType(materialIndex) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) return null;

    return MeshPhysicalMaterial;

  }

  extendMaterialParams(materialIndex, materialParams) {

    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {

      return Promise.resolve();

    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    materialParams.specularIntensity = extension.specularFactor !== undefined ? extension.specularFactor : 1.0;

    if (extension.specularTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'specularIntensityMap', extension.specularTexture));

    }

    const colorArray = extension.specularColorFactor || [1, 1, 1];
    materialParams.specularColor = new Color(colorArray[0], colorArray[1], colorArray[2]);

    if (extension.specularColorTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'specularColorMap', extension.specularColorTexture).then(function (texture) {

        texture.encoding = sRGBEncoding;

      }));

    }

    return Promise.all(pending);

  }

}

/**
 * BasisU Texture Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu
 */
class GLTFTextureBasisUExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.KHR_TEXTURE_BASISU;

  }

  loadTexture(textureIndex) {

    const parser = this.parser;
    const json = parser.json;

    const textureDef = json.textures[textureIndex];

    if (!textureDef.extensions || !textureDef.extensions[this.name]) {

      return null;

    }

    const extension = textureDef.extensions[this.name];
    const source = json.images[extension.source];
    const loader = parser.options.ktx2Loader;

    if (!loader) {

      if (json.extensionsRequired && json.extensionsRequired.indexOf(this.name) >= 0) {

        throw new Error('THREE.GLTFLoader: setKTX2Loader must be called before loading KTX2 textures');

      } else {

        // Assumes that the extension is optional and that a fallback texture is present
        return null;

      }

    }

    return parser.loadTextureImage(textureIndex, source, loader);

  }

}

/**
 * WebP Texture Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_texture_webp
 */
class GLTFTextureWebPExtension {

  constructor(parser) {

    this.parser = parser;
    this.name = EXTENSIONS.EXT_TEXTURE_WEBP;
    this.isSupported = null;

  }

  loadTexture(textureIndex) {

    const name = this.name;
    const parser = this.parser;
    const json = parser.json;

    const textureDef = json.textures[textureIndex];

    if (!textureDef.extensions || !textureDef.extensions[name]) {

      return null;

    }

    const extension = textureDef.extensions[name];
    const source = json.images[extension.source];

    let loader = parser.textureLoader;
    if (source.uri) {

      const handler = parser.options.manager.getHandler(source.uri);
      if (handler !== null) loader = handler;

    }

    return this.detectSupport().then(function (isSupported) {

      if (isSupported) return parser.loadTextureImage(textureIndex, source, loader);

      if (json.extensionsRequired && json.extensionsRequired.indexOf(name) >= 0) {

        throw new Error('THREE.GLTFLoader: WebP required by asset but unsupported.');

      }

      // Fall back to PNG or JPEG.
      return parser.loadTexture(textureIndex);

    });

  }

  detectSupport() {

    if (!this.isSupported) {

      this.isSupported = new Promise(function (resolve) {

        const image = new Image();

        // Lossy test image. Support for lossy images doesn't guarantee support for all
        // WebP images, unfortunately.
        image.src = '';

        image.onload = image.onerror = function () {

          resolve(image.height === 1);

        };

      });

    }

    return this.isSupported;

  }

}

/**
 * meshopt BufferView Compression Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_meshopt_compression
 */
class GLTFMeshoptCompression {

  constructor(parser) {

    this.name = EXTENSIONS.EXT_MESHOPT_COMPRESSION;
    this.parser = parser;

  }

  loadBufferView(index) {

    const json = this.parser.json;
    const bufferView = json.bufferViews[index];

    if (bufferView.extensions && bufferView.extensions[this.name]) {

      const extensionDef = bufferView.extensions[this.name];

      const buffer = this.parser.getDependency('buffer', extensionDef.buffer);
      const decoder = this.parser.options.meshoptDecoder;

      if (!decoder || !decoder.supported) {

        if (json.extensionsRequired && json.extensionsRequired.indexOf(this.name) >= 0) {

          throw new Error('THREE.GLTFLoader: setMeshoptDecoder must be called before loading compressed files');

        } else {

          // Assumes that the extension is optional and that fallback buffer data is present
          return null;

        }

      }

      return Promise.all([buffer, decoder.ready]).then(function (res) {

        const byteOffset = extensionDef.byteOffset || 0;
        const byteLength = extensionDef.byteLength || 0;

        const count = extensionDef.count;
        const stride = extensionDef.byteStride;

        const result = new ArrayBuffer(count * stride);
        const source = new Uint8Array(res[0], byteOffset, byteLength);

        decoder.decodeGltfBuffer(new Uint8Array(result), count, stride, source, extensionDef.mode, extensionDef.filter);
        return result;

      });

    } else {

      return null;

    }

  }

}

/* BINARY EXTENSION */
const BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
const BINARY_EXTENSION_HEADER_LENGTH = 12;
const BINARY_EXTENSION_CHUNK_TYPES = {JSON: 0x4E4F534A, BIN: 0x004E4942};

class GLTFBinaryExtension {

  constructor(data) {

    this.name = EXTENSIONS.KHR_BINARY_GLTF;
    this.content = null;
    this.body = null;

    const headerView = new DataView(data, 0, BINARY_EXTENSION_HEADER_LENGTH);

    this.header = {
      magic: LoaderUtils.decodeText(new Uint8Array(data.slice(0, 4))),
      version: headerView.getUint32(4, true),
      length: headerView.getUint32(8, true)
    };

    if (this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC) {

      throw new Error('THREE.GLTFLoader: Unsupported glTF-Binary header.');

    } else if (this.header.version < 2.0) {

      throw new Error('THREE.GLTFLoader: Legacy binary file detected.');

    }

    const chunkContentsLength = this.header.length - BINARY_EXTENSION_HEADER_LENGTH;
    const chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH);
    let chunkIndex = 0;

    while (chunkIndex < chunkContentsLength) {

      const chunkLength = chunkView.getUint32(chunkIndex, true);
      chunkIndex += 4;

      const chunkType = chunkView.getUint32(chunkIndex, true);
      chunkIndex += 4;

      if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {

        const contentArray = new Uint8Array(data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength);
        this.content = LoaderUtils.decodeText(contentArray);

      } else if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN) {

        const byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
        this.body = data.slice(byteOffset, byteOffset + chunkLength);

      }

      // Clients must ignore chunks with unknown types.

      chunkIndex += chunkLength;

    }

    if (this.content === null) {

      throw new Error('THREE.GLTFLoader: JSON content not found.');

    }

  }

}

/**
 * DRACO Mesh Compression Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
 */
class GLTFDracoMeshCompressionExtension {

  constructor(json, dracoLoader) {

    if (!dracoLoader) {

      throw new Error('THREE.GLTFLoader: No DRACOLoader instance provided.');

    }

    this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
    this.json = json;
    this.dracoLoader = dracoLoader;
    this.dracoLoader.preload();

  }

  decodePrimitive(primitive, parser) {

    const json = this.json;
    const dracoLoader = this.dracoLoader;
    const bufferViewIndex = primitive.extensions[this.name].bufferView;
    const gltfAttributeMap = primitive.extensions[this.name].attributes;
    const threeAttributeMap = {};
    const attributeNormalizedMap = {};
    const attributeTypeMap = {};

    for (const attributeName in gltfAttributeMap) {

      const threeAttributeName = ATTRIBUTES[attributeName] || attributeName.toLowerCase();

      threeAttributeMap[threeAttributeName] = gltfAttributeMap[attributeName];

    }

    for (const attributeName in primitive.attributes) {

      const threeAttributeName = ATTRIBUTES[attributeName] || attributeName.toLowerCase();

      if (gltfAttributeMap[attributeName] !== undefined) {

        const accessorDef = json.accessors[primitive.attributes[attributeName]];
        const componentType = WEBGL_COMPONENT_TYPES[accessorDef.componentType];

        attributeTypeMap[threeAttributeName] = componentType;
        attributeNormalizedMap[threeAttributeName] = accessorDef.normalized === true;

      }

    }

    return parser.getDependency('bufferView', bufferViewIndex).then(function (bufferView) {

      return new Promise(function (resolve) {

        dracoLoader.decodeDracoFile(bufferView, function (geometry) {

          for (const attributeName in geometry.attributes) {

            const attribute = geometry.attributes[attributeName];
            const normalized = attributeNormalizedMap[attributeName];

            if (normalized !== undefined) attribute.normalized = normalized;

          }

          resolve(geometry);

        }, threeAttributeMap, attributeTypeMap);

      });

    });

  }

}

/**
 * Texture Transform Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
 */
class GLTFTextureTransformExtension {

  constructor() {

    this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;

  }

  extendTexture(texture, transform) {

    if (transform.texCoord !== undefined) {

      console.warn('THREE.GLTFLoader: Custom UV sets in "' + this.name + '" extension not yet supported.');

    }

    if (transform.offset === undefined && transform.rotation === undefined && transform.scale === undefined) {

      // See https://github.com/mrdoob/three.js/issues/21819.
      return texture;

    }

    texture = texture.clone();

    if (transform.offset !== undefined) {

      texture.offset.fromArray(transform.offset);

    }

    if (transform.rotation !== undefined) {

      texture.rotation = transform.rotation;

    }

    if (transform.scale !== undefined) {

      texture.repeat.fromArray(transform.scale);

    }

    texture.needsUpdate = true;

    return texture;

  }

}

/**
 * Specular-Glossiness Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Archived/KHR_materials_pbrSpecularGlossiness
 */

/**
 * A sub class of StandardMaterial with some of the functionality
 * changed via the `onBeforeCompile` callback
 * @pailhead
 */
class GLTFMeshStandardSGMaterial extends MeshStandardMaterial {

  constructor(params) {

    super();

    this.isGLTFSpecularGlossinessMaterial = true;

    //various chunks that need replacing
    const specularMapParsFragmentChunk = [
      '#ifdef USE_SPECULARMAP',
      '	uniform sampler2D specularMap;',
      '#endif'
    ].join('\n');

    const glossinessMapParsFragmentChunk = [
      '#ifdef USE_GLOSSINESSMAP',
      '	uniform sampler2D glossinessMap;',
      '#endif'
    ].join('\n');

    const specularMapFragmentChunk = [
      'vec3 specularFactor = specular;',
      '#ifdef USE_SPECULARMAP',
      '	vec4 texelSpecular = texture2D( specularMap, vUv );',
      '	texelSpecular = sRGBToLinear( texelSpecular );',
      '	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture',
      '	specularFactor *= texelSpecular.rgb;',
      '#endif'
    ].join('\n');

    const glossinessMapFragmentChunk = [
      'float glossinessFactor = glossiness;',
      '#ifdef USE_GLOSSINESSMAP',
      '	vec4 texelGlossiness = texture2D( glossinessMap, vUv );',
      '	// reads channel A, compatible with a glTF Specular-Glossiness (RGBA) texture',
      '	glossinessFactor *= texelGlossiness.a;',
      '#endif'
    ].join('\n');

    const lightPhysicalFragmentChunk = [
      'PhysicalMaterial material;',
      'material.diffuseColor = diffuseColor.rgb * ( 1. - max( specularFactor.r, max( specularFactor.g, specularFactor.b ) ) );',
      'vec3 dxy = max( abs( dFdx( geometryNormal ) ), abs( dFdy( geometryNormal ) ) );',
      'float geometryRoughness = max( max( dxy.x, dxy.y ), dxy.z );',
      'material.roughness = max( 1.0 - glossinessFactor, 0.0525 ); // 0.0525 corresponds to the base mip of a 256 cubemap.',
      'material.roughness += geometryRoughness;',
      'material.roughness = min( material.roughness, 1.0 );',
      'material.specularColor = specularFactor;',
    ].join('\n');

    const uniforms = {
      specular: {value: new Color().setHex(0xffffff)},
      glossiness: {value: 1},
      specularMap: {value: null},
      glossinessMap: {value: null}
    };

    this._extraUniforms = uniforms;

    this.onBeforeCompile = function (shader) {

      for (const uniformName in uniforms) {

        shader.uniforms[uniformName] = uniforms[uniformName];

      }

      shader.fragmentShader = shader.fragmentShader
        .replace('uniform float roughness;', 'uniform vec3 specular;')
        .replace('uniform float metalness;', 'uniform float glossiness;')
        .replace('#include <roughnessmap_pars_fragment>', specularMapParsFragmentChunk)
        .replace('#include <metalnessmap_pars_fragment>', glossinessMapParsFragmentChunk)
        .replace('#include <roughnessmap_fragment>', specularMapFragmentChunk)
        .replace('#include <metalnessmap_fragment>', glossinessMapFragmentChunk)
        .replace('#include <lights_physical_fragment>', lightPhysicalFragmentChunk);

    };

    Object.defineProperties(this, {

      specular: {
        get: function () {

          return uniforms.specular.value;

        },
        set: function (v) {

          uniforms.specular.value = v;

        }
      },

      specularMap: {
        get: function () {

          return uniforms.specularMap.value;

        },
        set: function (v) {

          uniforms.specularMap.value = v;

          if (v) {

            this.defines.USE_SPECULARMAP = ''; // USE_UV is set by the renderer for specular maps

          } else {

            delete this.defines.USE_SPECULARMAP;

          }

        }
      },

      glossiness: {
        get: function () {

          return uniforms.glossiness.value;

        },
        set: function (v) {

          uniforms.glossiness.value = v;

        }
      },

      glossinessMap: {
        get: function () {

          return uniforms.glossinessMap.value;

        },
        set: function (v) {

          uniforms.glossinessMap.value = v;

          if (v) {

            this.defines.USE_GLOSSINESSMAP = '';
            this.defines.USE_UV = '';

          } else {

            delete this.defines.USE_GLOSSINESSMAP;
            delete this.defines.USE_UV;

          }

        }
      }

    });

    delete this.metalness;
    delete this.roughness;
    delete this.metalnessMap;
    delete this.roughnessMap;

    this.setValues(params);

  }

  copy(source) {

    super.copy(source);

    this.specularMap = source.specularMap;
    this.specular.copy(source.specular);
    this.glossinessMap = source.glossinessMap;
    this.glossiness = source.glossiness;
    delete this.metalness;
    delete this.roughness;
    delete this.metalnessMap;
    delete this.roughnessMap;
    return this;

  }

}


class GLTFMaterialsPbrSpecularGlossinessExtension {

  constructor() {

    this.name = EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS;

    this.specularGlossinessParams = [
      'color',
      'map',
      'lightMap',
      'lightMapIntensity',
      'aoMap',
      'aoMapIntensity',
      'emissive',
      'emissiveIntensity',
      'emissiveMap',
      'bumpMap',
      'bumpScale',
      'normalMap',
      'normalMapType',
      'displacementMap',
      'displacementScale',
      'displacementBias',
      'specularMap',
      'specular',
      'glossinessMap',
      'glossiness',
      'alphaMap',
      'envMap',
      'envMapIntensity',
      'refractionRatio',
    ];

  }

  getMaterialType() {

    return GLTFMeshStandardSGMaterial;

  }

  extendParams(materialParams, materialDef, parser) {

    const pbrSpecularGlossiness = materialDef.extensions[this.name];

    materialParams.color = new Color(1.0, 1.0, 1.0);
    materialParams.opacity = 1.0;

    const pending = [];

    if (Array.isArray(pbrSpecularGlossiness.diffuseFactor)) {

      const array = pbrSpecularGlossiness.diffuseFactor;

      materialParams.color.fromArray(array);
      materialParams.opacity = array[3];

    }

    if (pbrSpecularGlossiness.diffuseTexture !== undefined) {

      pending.push(parser.assignTexture(materialParams, 'map', pbrSpecularGlossiness.diffuseTexture));

    }

    materialParams.emissive = new Color(0.0, 0.0, 0.0);
    materialParams.glossiness = pbrSpecularGlossiness.glossinessFactor !== undefined ? pbrSpecularGlossiness.glossinessFactor : 1.0;
    materialParams.specular = new Color(1.0, 1.0, 1.0);

    if (Array.isArray(pbrSpecularGlossiness.specularFactor)) {

      materialParams.specular.fromArray(pbrSpecularGlossiness.specularFactor);

    }

    if (pbrSpecularGlossiness.specularGlossinessTexture !== undefined) {

      const specGlossMapDef = pbrSpecularGlossiness.specularGlossinessTexture;
      pending.push(parser.assignTexture(materialParams, 'glossinessMap', specGlossMapDef));
      pending.push(parser.assignTexture(materialParams, 'specularMap', specGlossMapDef));

    }

    return Promise.all(pending);

  }

  createMaterial(materialParams) {

    const material = new GLTFMeshStandardSGMaterial(materialParams);
    material.fog = true;

    material.color = materialParams.color;

    material.map = materialParams.map === undefined ? null : materialParams.map;

    material.lightMap = null;
    material.lightMapIntensity = 1.0;

    material.aoMap = materialParams.aoMap === undefined ? null : materialParams.aoMap;
    material.aoMapIntensity = 1.0;

    material.emissive = materialParams.emissive;
    material.emissiveIntensity = 1.0;
    material.emissiveMap = materialParams.emissiveMap === undefined ? null : materialParams.emissiveMap;

    material.bumpMap = materialParams.bumpMap === undefined ? null : materialParams.bumpMap;
    material.bumpScale = 1;

    material.normalMap = materialParams.normalMap === undefined ? null : materialParams.normalMap;
    material.normalMapType = TangentSpaceNormalMap;

    if (materialParams.normalScale) material.normalScale = materialParams.normalScale;

    material.displacementMap = null;
    material.displacementScale = 1;
    material.displacementBias = 0;

    material.specularMap = materialParams.specularMap === undefined ? null : materialParams.specularMap;
    material.specular = materialParams.specular;

    material.glossinessMap = materialParams.glossinessMap === undefined ? null : materialParams.glossinessMap;
    material.glossiness = materialParams.glossiness;

    material.alphaMap = null;

    material.envMap = materialParams.envMap === undefined ? null : materialParams.envMap;
    material.envMapIntensity = 1.0;

    material.refractionRatio = 0.98;

    return material;

  }

}

/**
 * Mesh Quantization Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
 */
class GLTFMeshQuantizationExtension {

  constructor() {

    this.name = EXTENSIONS.KHR_MESH_QUANTIZATION;

  }

}

/*********************************/
/********** INTERPOLATION ********/
/*********************************/

// Spline Interpolation
// Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
class GLTFCubicSplineInterpolant extends Interpolant {

  constructor(parameterPositions, sampleValues, sampleSize, resultBuffer) {

    super(parameterPositions, sampleValues, sampleSize, resultBuffer);

  }

  copySampleValue_(index) {

    // Copies a sample value to the result buffer. See description of glTF
    // CUBICSPLINE values layout in interpolate_() function below.

    const result = this.resultBuffer,
      values = this.sampleValues,
      valueSize = this.valueSize,
      offset = index * valueSize * 3 + valueSize;

    for (let i = 0; i !== valueSize; i++) {

      result[i] = values[offset + i];

    }

    return result;

  }

}

GLTFCubicSplineInterpolant.prototype.beforeStart_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_;

GLTFCubicSplineInterpolant.prototype.afterEnd_ = GLTFCubicSplineInterpolant.prototype.copySampleValue_;

GLTFCubicSplineInterpolant.prototype.interpolate_ = function (i1, t0, t, t1) {

  const result = this.resultBuffer;
  const values = this.sampleValues;
  const stride = this.valueSize;

  const stride2 = stride * 2;
  const stride3 = stride * 3;

  const td = t1 - t0;

  const p = (t - t0) / td;
  const pp = p * p;
  const ppp = pp * p;

  const offset1 = i1 * stride3;
  const offset0 = offset1 - stride3;

  const s2 = -2 * ppp + 3 * pp;
  const s3 = ppp - pp;
  const s0 = 1 - s2;
  const s1 = s3 - pp + p;

  // Layout of keyframe output values for CUBICSPLINE animations:
  //   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]
  for (let i = 0; i !== stride; i++) {

    const p0 = values[offset0 + i + stride]; // splineVertex_k
    const m0 = values[offset0 + i + stride2] * td; // outTangent_k * (t_k+1 - t_k)
    const p1 = values[offset1 + i + stride]; // splineVertex_k+1
    const m1 = values[offset1 + i] * td; // inTangent_k+1 * (t_k+1 - t_k)

    result[i] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;

  }

  return result;

};

const _q = new Quaternion();

class GLTFCubicSplineQuaternionInterpolant extends GLTFCubicSplineInterpolant {

  interpolate_(i1, t0, t, t1) {

    const result = super.interpolate_(i1, t0, t, t1);

    _q.fromArray(result).normalize().toArray(result);

    return result;

  }

}


/*********************************/
/********** INTERNALS ************/
/*********************************/

/* CONSTANTS */

const WEBGL_CONSTANTS = {
  FLOAT: 5126,
  //FLOAT_MAT2: 35674,
  FLOAT_MAT3: 35675,
  FLOAT_MAT4: 35676,
  FLOAT_VEC2: 35664,
  FLOAT_VEC3: 35665,
  FLOAT_VEC4: 35666,
  LINEAR: 9729,
  REPEAT: 10497,
  SAMPLER_2D: 35678,
  POINTS: 0,
  LINES: 1,
  LINE_LOOP: 2,
  LINE_STRIP: 3,
  TRIANGLES: 4,
  TRIANGLE_STRIP: 5,
  TRIANGLE_FAN: 6,
  UNSIGNED_BYTE: 5121,
  UNSIGNED_SHORT: 5123
};

const WEBGL_COMPONENT_TYPES = {
  5120: Int8Array,
  5121: Uint8Array,
  5122: Int16Array,
  5123: Uint16Array,
  5125: Uint32Array,
  5126: Float32Array
};

const WEBGL_FILTERS = {
  9728: NearestFilter,
  9729: LinearFilter,
  9984: NearestMipmapNearestFilter,
  9985: LinearMipmapNearestFilter,
  9986: NearestMipmapLinearFilter,
  9987: LinearMipmapLinearFilter
};

const WEBGL_WRAPPINGS = {
  33071: ClampToEdgeWrapping,
  33648: MirroredRepeatWrapping,
  10497: RepeatWrapping
};

const WEBGL_TYPE_SIZES = {
  'SCALAR': 1,
  'VEC2': 2,
  'VEC3': 3,
  'VEC4': 4,
  'MAT2': 4,
  'MAT3': 9,
  'MAT4': 16
};

const ATTRIBUTES = {
  POSITION: 'position',
  NORMAL: 'normal',
  TANGENT: 'tangent',
  TEXCOORD_0: 'uv',
  TEXCOORD_1: 'uv2',
  COLOR_0: 'color',
  WEIGHTS_0: 'skinWeight',
  JOINTS_0: 'skinIndex',
};

const PATH_PROPERTIES = {
  scale: 'scale',
  translation: 'position',
  rotation: 'quaternion',
  weights: 'morphTargetInfluences'
};

const INTERPOLATION = {
  CUBICSPLINE: undefined, // We use a custom interpolant (GLTFCubicSplineInterpolation) for CUBICSPLINE tracks. Each
  // keyframe track will be initialized with a default interpolation type, then modified.
  LINEAR: InterpolateLinear,
  STEP: InterpolateDiscrete
};

const ALPHA_MODES = {
  OPAQUE: 'OPAQUE',
  MASK: 'MASK',
  BLEND: 'BLEND'
};

/**
 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
 */
function createDefaultMaterial(cache) {

  if (cache['DefaultMaterial'] === undefined) {

    cache['DefaultMaterial'] = new MeshStandardMaterial({
      color: 0xFFFFFF,
      emissive: 0x000000,
      metalness: 1,
      roughness: 1,
      transparent: false,
      depthTest: true,
      side: FrontSide
    });

  }

  return cache['DefaultMaterial'];

}

function addUnknownExtensionsToUserData(knownExtensions, object, objectDef) {

  // Add unknown glTF extensions to an object's userData.

  for (const name in objectDef.extensions) {

    if (knownExtensions[name] === undefined) {

      object.userData.gltfExtensions = object.userData.gltfExtensions || {};
      object.userData.gltfExtensions[name] = objectDef.extensions[name];

    }

  }

}

/**
 * @param {Object3D|Material|BufferGeometry} object
 * @param {GLTF.definition} gltfDef
 */
function assignExtrasToUserData(object, gltfDef) {

  if (gltfDef.extras !== undefined) {

    if (typeof gltfDef.extras === 'object') {

      Object.assign(object.userData, gltfDef.extras);

    } else {

      console.warn('THREE.GLTFLoader: Ignoring primitive type .extras, ' + gltfDef.extras);

    }

  }

}

/**
 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
 *
 * @param {BufferGeometry} geometry
 * @param {Array<GLTF.Target>} targets
 * @param {GLTFParser} parser
 * @return {Promise<BufferGeometry>}
 */
function addMorphTargets(geometry, targets, parser) {

  let hasMorphPosition = false;
  let hasMorphNormal = false;

  for (let i = 0, il = targets.length; i < il; i++) {

    const target = targets[i];

    if (target.POSITION !== undefined) hasMorphPosition = true;
    if (target.NORMAL !== undefined) hasMorphNormal = true;

    if (hasMorphPosition && hasMorphNormal) break;

  }

  if (!hasMorphPosition && !hasMorphNormal) return Promise.resolve(geometry);

  const pendingPositionAccessors = [];
  const pendingNormalAccessors = [];

  for (let i = 0, il = targets.length; i < il; i++) {

    const target = targets[i];

    if (hasMorphPosition) {

      const pendingAccessor = target.POSITION !== undefined
        ? parser.getDependency('accessor', target.POSITION)
        : geometry.attributes.position;

      pendingPositionAccessors.push(pendingAccessor);

    }

    if (hasMorphNormal) {

      const pendingAccessor = target.NORMAL !== undefined
        ? parser.getDependency('accessor', target.NORMAL)
        : geometry.attributes.normal;

      pendingNormalAccessors.push(pendingAccessor);

    }

  }

  return Promise.all([
    Promise.all(pendingPositionAccessors),
    Promise.all(pendingNormalAccessors)
  ]).then(function (accessors) {

    const morphPositions = accessors[0];
    const morphNormals = accessors[1];

    if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
    if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;
    geometry.morphTargetsRelative = true;

    return geometry;

  });

}

/**
 * @param {Mesh} mesh
 * @param {GLTF.Mesh} meshDef
 */
function updateMorphTargets(mesh, meshDef) {

  mesh.updateMorphTargets();

  if (meshDef.weights !== undefined) {

    for (let i = 0, il = meshDef.weights.length; i < il; i++) {

      mesh.morphTargetInfluences[i] = meshDef.weights[i];

    }

  }

  // .extras has user-defined data, so check that .extras.targetNames is an array.
  if (meshDef.extras && Array.isArray(meshDef.extras.targetNames)) {

    const targetNames = meshDef.extras.targetNames;

    if (mesh.morphTargetInfluences.length === targetNames.length) {

      mesh.morphTargetDictionary = {};

      for (let i = 0, il = targetNames.length; i < il; i++) {

        mesh.morphTargetDictionary[targetNames[i]] = i;

      }

    } else {

      console.warn('THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names.');

    }

  }

}

function createPrimitiveKey(primitiveDef) {

  const dracoExtension = primitiveDef.extensions && primitiveDef.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION];
  let geometryKey;

  if (dracoExtension) {

    geometryKey = 'draco:' + dracoExtension.bufferView
      + ':' + dracoExtension.indices
      + ':' + createAttributesKey(dracoExtension.attributes);

  } else {

    geometryKey = primitiveDef.indices + ':' + createAttributesKey(primitiveDef.attributes) + ':' + primitiveDef.mode;

  }

  return geometryKey;

}

function createAttributesKey(attributes) {

  let attributesKey = '';

  const keys = Object.keys(attributes).sort();

  for (let i = 0, il = keys.length; i < il; i++) {

    attributesKey += keys[i] + ':' + attributes[keys[i]] + ';';

  }

  return attributesKey;

}

function getNormalizedComponentScale(constructor) {

  // Reference:
  // https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization#encoding-quantized-data

  switch (constructor) {

    case Int8Array:
      return 1 / 127;

    case Uint8Array:
      return 1 / 255;

    case Int16Array:
      return 1 / 32767;

    case Uint16Array:
      return 1 / 65535;

    default:
      throw new Error('THREE.GLTFLoader: Unsupported normalized accessor component type.');

  }

}

/* GLTF PARSER */

class GLTFParser {

  constructor(json = {}, options = {}) {

    this.json = json;
    this.extensions = {};
    this.plugins = {};
    this.options = options;

    // loader object cache
    this.cache = new GLTFRegistry();

    // associations between Three.js objects and glTF elements
    this.associations = new Map();

    // BufferGeometry caching
    this.primitiveCache = {};

    // Object3D instance caches
    this.meshCache = {refs: {}, uses: {}};
    this.cameraCache = {refs: {}, uses: {}};
    this.lightCache = {refs: {}, uses: {}};

    this.textureCache = {};

    // Track node names, to ensure no duplicates
    this.nodeNamesUsed = {};

    // Use an ImageBitmapLoader if imageBitmaps are supported. Moves much of the
    // expensive work of uploading a texture to the GPU off the main thread.
    if (typeof createImageBitmap !== 'undefined' && /Firefox|Safari/.test(navigator.userAgent) === false) {

      this.textureLoader = new ImageBitmapLoader(this.options.manager);

    } else {

      this.textureLoader = new TextureLoader(this.options.manager);

    }

    this.textureLoader.setCrossOrigin(this.options.crossOrigin);
    this.textureLoader.setRequestHeader(this.options.requestHeader);

    this.fileLoader = new FileLoader(this.options.manager);
    this.fileLoader.setResponseType('arraybuffer');

    if (this.options.crossOrigin === 'use-credentials') {

      this.fileLoader.setWithCredentials(true);

    }

  }

  setExtensions(extensions) {

    this.extensions = extensions;

  }

  setPlugins(plugins) {

    this.plugins = plugins;

  }

  parse(onLoad, onError) {

    const parser = this;
    const json = this.json;
    const extensions = this.extensions;

    // Clear the loader cache
    this.cache.removeAll();

    // Mark the special nodes/meshes in json for efficient parse
    this._invokeAll(function (ext) {

      return ext._markDefs && ext._markDefs();

    });

    Promise.all(this._invokeAll(function (ext) {

      return ext.beforeRoot && ext.beforeRoot();

    })).then(function () {

      return Promise.all([

        parser.getDependencies('scene'),
        parser.getDependencies('animation'),
        parser.getDependencies('camera'),

      ]);

    }).then(function (dependencies) {

      const result = {
        scene: dependencies[0][json.scene || 0],
        scenes: dependencies[0],
        animations: dependencies[1],
        cameras: dependencies[2],
        asset: json.asset,
        parser: parser,
        userData: {}
      };

      addUnknownExtensionsToUserData(extensions, result, json);

      assignExtrasToUserData(result, json);

      Promise.all(parser._invokeAll(function (ext) {

        return ext.afterRoot && ext.afterRoot(result);

      })).then(function () {

        onLoad(result);

      });

    }).catch(onError);

  }

  /**
   * Marks the special nodes/meshes in json for efficient parse.
   */
  _markDefs() {

    const nodeDefs = this.json.nodes || [];
    const skinDefs = this.json.skins || [];
    const meshDefs = this.json.meshes || [];

    // Nothing in the node definition indicates whether it is a Bone or an
    // Object3D. Use the skins' joint references to mark bones.
    for (let skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex++) {

      const joints = skinDefs[skinIndex].joints;

      for (let i = 0, il = joints.length; i < il; i++) {

        nodeDefs[joints[i]].isBone = true;

      }

    }

    // Iterate over all nodes, marking references to shared resources,
    // as well as skeleton joints.
    for (let nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex++) {

      const nodeDef = nodeDefs[nodeIndex];

      if (nodeDef.mesh !== undefined) {

        this._addNodeRef(this.meshCache, nodeDef.mesh);

        // Nothing in the mesh definition indicates whether it is
        // a SkinnedMesh or Mesh. Use the node's mesh reference
        // to mark SkinnedMesh if node has skin.
        if (nodeDef.skin !== undefined) {

          meshDefs[nodeDef.mesh].isSkinnedMesh = true;

        }

      }

      if (nodeDef.camera !== undefined) {

        this._addNodeRef(this.cameraCache, nodeDef.camera);

      }

    }

  }

  /**
   * Counts references to shared node / Object3D resources. These resources
   * can be reused, or "instantiated", at multiple nodes in the scene
   * hierarchy. Mesh, Camera, and Light instances are instantiated and must
   * be marked. Non-scenegraph resources (like Materials, Geometries, and
   * Textures) can be reused directly and are not marked here.
   *
   * Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
   */
  _addNodeRef(cache, index) {

    if (index === undefined) return;

    if (cache.refs[index] === undefined) {

      cache.refs[index] = cache.uses[index] = 0;

    }

    cache.refs[index]++;

  }

  /** Returns a reference to a shared resource, cloning it if necessary. */
  _getNodeRef(cache, index, object) {

    if (cache.refs[index] <= 1) return object;

    const ref = object.clone();

    // Propagates mappings to the cloned object, prevents mappings on the
    // original object from being lost.
    const updateMappings = (original, clone) => {

      const mappings = this.associations.get(original);
      if (mappings != null) {

        this.associations.set(clone, mappings);

      }

      for (const [i, child] of original.children.entries()) {

        updateMappings(child, clone.children[i]);

      }

    };

    updateMappings(object, ref);

    ref.name += '_instance_' + (cache.uses[index]++);

    return ref;

  }

  _invokeOne(func) {

    const extensions = Object.values(this.plugins);
    extensions.push(this);

    for (let i = 0; i < extensions.length; i++) {

      const result = func(extensions[i]);

      if (result) return result;

    }

    return null;

  }

  _invokeAll(func) {

    const extensions = Object.values(this.plugins);
    extensions.unshift(this);

    const pending = [];

    for (let i = 0; i < extensions.length; i++) {

      const result = func(extensions[i]);

      if (result) pending.push(result);

    }

    return pending;

  }

  /**
   * Requests the specified dependency asynchronously, with caching.
   * @param {string} type
   * @param {number} index
   * @return {Promise<Object3D|Material|THREE.Texture|AnimationClip|ArrayBuffer|Object>}
   */
  getDependency(type, index) {

    const cacheKey = type + ':' + index;
    let dependency = this.cache.get(cacheKey);

    if (!dependency) {

      switch (type) {

        case 'scene':
          dependency = this.loadScene(index);
          break;

        case 'node':
          dependency = this.loadNode(index);
          break;

        case 'mesh':
          dependency = this._invokeOne(function (ext) {

            return ext.loadMesh && ext.loadMesh(index);

          });
          break;

        case 'accessor':
          dependency = this.loadAccessor(index);
          break;

        case 'bufferView':
          dependency = this._invokeOne(function (ext) {

            return ext.loadBufferView && ext.loadBufferView(index);

          });
          break;

        case 'buffer':
          dependency = this.loadBuffer(index);
          break;

        case 'material':
          dependency = this._invokeOne(function (ext) {

            return ext.loadMaterial && ext.loadMaterial(index);

          });
          break;

        case 'texture':
          dependency = this._invokeOne(function (ext) {

            return ext.loadTexture && ext.loadTexture(index);

          });
          break;

        case 'skin':
          dependency = this.loadSkin(index);
          break;

        case 'animation':
          dependency = this.loadAnimation(index);
          break;

        case 'camera':
          dependency = this.loadCamera(index);
          break;

        default:
          throw new Error('Unknown type: ' + type);

      }

      this.cache.add(cacheKey, dependency);

    }

    return dependency;

  }

  /**
   * Requests all dependencies of the specified type asynchronously, with caching.
   * @param {string} type
   * @return {Promise<Array<Object>>}
   */
  getDependencies(type) {

    let dependencies = this.cache.get(type);

    if (!dependencies) {

      const parser = this;
      const defs = this.json[type + (type === 'mesh' ? 'es' : 's')] || [];

      dependencies = Promise.all(defs.map(function (def, index) {

        return parser.getDependency(type, index);

      }));

      this.cache.add(type, dependencies);

    }

    return dependencies;

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
   * @param {number} bufferIndex
   * @return {Promise<ArrayBuffer>}
   */
  loadBuffer(bufferIndex) {

    const bufferDef = this.json.buffers[bufferIndex];
    const loader = this.fileLoader;

    if (bufferDef.type && bufferDef.type !== 'arraybuffer') {

      throw new Error('THREE.GLTFLoader: ' + bufferDef.type + ' buffer type is not supported.');

    }

    // If present, GLB container is required to be the first buffer.
    if (bufferDef.uri === undefined && bufferIndex === 0) {

      return Promise.resolve(this.extensions[EXTENSIONS.KHR_BINARY_GLTF].body);

    }

    const options = this.options;

    return new Promise(function (resolve, reject) {

      loader.load(LoaderUtils.resolveURL(bufferDef.uri, options.path), resolve, undefined, function () {

        reject(new Error('THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".'));

      });

    });

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
   * @param {number} bufferViewIndex
   * @return {Promise<ArrayBuffer>}
   */
  loadBufferView(bufferViewIndex) {

    const bufferViewDef = this.json.bufferViews[bufferViewIndex];

    return this.getDependency('buffer', bufferViewDef.buffer).then(function (buffer) {

      const byteLength = bufferViewDef.byteLength || 0;
      const byteOffset = bufferViewDef.byteOffset || 0;
      return buffer.slice(byteOffset, byteOffset + byteLength);

    });

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
   * @param {number} accessorIndex
   * @return {Promise<BufferAttribute|InterleavedBufferAttribute>}
   */
  loadAccessor(accessorIndex) {

    const parser = this;
    const json = this.json;

    const accessorDef = this.json.accessors[accessorIndex];

    if (accessorDef.bufferView === undefined && accessorDef.sparse === undefined) {

      // Ignore empty accessors, which may be used to declare runtime
      // information about attributes coming from another source (e.g. Draco
      // compression extension).
      return Promise.resolve(null);

    }

    const pendingBufferViews = [];

    if (accessorDef.bufferView !== undefined) {

      pendingBufferViews.push(this.getDependency('bufferView', accessorDef.bufferView));

    } else {

      pendingBufferViews.push(null);

    }

    if (accessorDef.sparse !== undefined) {

      pendingBufferViews.push(this.getDependency('bufferView', accessorDef.sparse.indices.bufferView));
      pendingBufferViews.push(this.getDependency('bufferView', accessorDef.sparse.values.bufferView));

    }

    return Promise.all(pendingBufferViews).then(function (bufferViews) {

      const bufferView = bufferViews[0];

      const itemSize = WEBGL_TYPE_SIZES[accessorDef.type];
      const TypedArray = WEBGL_COMPONENT_TYPES[accessorDef.componentType];

      // For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.
      const elementBytes = TypedArray.BYTES_PER_ELEMENT;
      const itemBytes = elementBytes * itemSize;
      const byteOffset = accessorDef.byteOffset || 0;
      const byteStride = accessorDef.bufferView !== undefined ? json.bufferViews[accessorDef.bufferView].byteStride : undefined;
      const normalized = accessorDef.normalized === true;
      let array, bufferAttribute;

      // The buffer is not interleaved if the stride is the item size in bytes.
      if (byteStride && byteStride !== itemBytes) {

        // Each "slice" of the buffer, as defined by 'count' elements of 'byteStride' bytes, gets its own InterleavedBuffer
        // This makes sure that IBA.count reflects accessor.count properly
        const ibSlice = Math.floor(byteOffset / byteStride);
        const ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType + ':' + ibSlice + ':' + accessorDef.count;
        let ib = parser.cache.get(ibCacheKey);

        if (!ib) {

          array = new TypedArray(bufferView, ibSlice * byteStride, accessorDef.count * byteStride / elementBytes);

          // Integer parameters to IB/IBA are in array elements, not bytes.
          ib = new InterleavedBuffer(array, byteStride / elementBytes);

          parser.cache.add(ibCacheKey, ib);

        }

        bufferAttribute = new InterleavedBufferAttribute(ib, itemSize, (byteOffset % byteStride) / elementBytes, normalized);

      } else {

        if (bufferView === null) {

          array = new TypedArray(accessorDef.count * itemSize);

        } else {

          array = new TypedArray(bufferView, byteOffset, accessorDef.count * itemSize);

        }

        bufferAttribute = new BufferAttribute(array, itemSize, normalized);

      }

      // https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
      if (accessorDef.sparse !== undefined) {

        const itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
        const TypedArrayIndices = WEBGL_COMPONENT_TYPES[accessorDef.sparse.indices.componentType];

        const byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
        const byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;

        const sparseIndices = new TypedArrayIndices(bufferViews[1], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices);
        const sparseValues = new TypedArray(bufferViews[2], byteOffsetValues, accessorDef.sparse.count * itemSize);

        if (bufferView !== null) {

          // Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
          bufferAttribute = new BufferAttribute(bufferAttribute.array.slice(), bufferAttribute.itemSize, bufferAttribute.normalized);

        }

        for (let i = 0, il = sparseIndices.length; i < il; i++) {

          const index = sparseIndices[i];

          bufferAttribute.setX(index, sparseValues[i * itemSize]);
          if (itemSize >= 2) bufferAttribute.setY(index, sparseValues[i * itemSize + 1]);
          if (itemSize >= 3) bufferAttribute.setZ(index, sparseValues[i * itemSize + 2]);
          if (itemSize >= 4) bufferAttribute.setW(index, sparseValues[i * itemSize + 3]);
          if (itemSize >= 5) throw new Error('THREE.GLTFLoader: Unsupported itemSize in sparse BufferAttribute.');

        }

      }

      return bufferAttribute;

    });

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
   * @param {number} textureIndex
   * @return {Promise<THREE.Texture>}
   */
  loadTexture(textureIndex) {

    const json = this.json;
    const options = this.options;
    const textureDef = json.textures[textureIndex];
    const source = json.images[textureDef.source];

    let loader = this.textureLoader;

    if (source.uri) {

      const handler = options.manager.getHandler(source.uri);
      if (handler !== null) loader = handler;

    }

    return this.loadTextureImage(textureIndex, source, loader);

  }

  loadTextureImage(textureIndex, source, loader) {

    const parser = this;
    const json = this.json;
    const options = this.options;

    const textureDef = json.textures[textureIndex];

    const cacheKey = (source.uri || source.bufferView) + ':' + textureDef.sampler;

    if (this.textureCache[cacheKey]) {

      // See https://github.com/mrdoob/three.js/issues/21559.
      return this.textureCache[cacheKey];

    }

    const URL = self.URL || self.webkitURL;

    let sourceURI = source.uri || '';
    let isObjectURL = false;

    if (source.bufferView !== undefined) {

      // Load binary image data from bufferView, if provided.

      sourceURI = parser.getDependency('bufferView', source.bufferView).then(function (bufferView) {

        isObjectURL = true;
        const blob = new Blob([bufferView], {type: source.mimeType});
        sourceURI = URL.createObjectURL(blob);
        return sourceURI;

      });

    } else if (source.uri === undefined) {

      throw new Error('THREE.GLTFLoader: Image ' + textureIndex + ' is missing URI and bufferView');

    }

    const promise = Promise.resolve(sourceURI).then(function (sourceURI) {

      return new Promise(function (resolve, reject) {

        let onLoad = resolve;

        if (loader.isImageBitmapLoader === true) {

          onLoad = function (imageBitmap) {

            const texture = new Texture(imageBitmap);
            texture.needsUpdate = true;

            resolve(texture);

          };

        }

        loader.load(LoaderUtils.resolveURL(sourceURI, options.path), onLoad, undefined, reject);

      });

    }).then(function (texture) {

      // Clean up resources and configure Texture.

      if (isObjectURL === true) {

        URL.revokeObjectURL(sourceURI);

      }

      texture.flipY = false;

      if (textureDef.name) texture.name = textureDef.name;

      const samplers = json.samplers || {};
      const sampler = samplers[textureDef.sampler] || {};

      texture.magFilter = WEBGL_FILTERS[sampler.magFilter] || LinearFilter;
      texture.minFilter = WEBGL_FILTERS[sampler.minFilter] || LinearMipmapLinearFilter;
      texture.wrapS = WEBGL_WRAPPINGS[sampler.wrapS] || RepeatWrapping;
      texture.wrapT = WEBGL_WRAPPINGS[sampler.wrapT] || RepeatWrapping;

      parser.associations.set(texture, {textures: textureIndex});

      return texture;

    }).catch(function () {

      console.error('THREE.GLTFLoader: Couldn\'t load texture', sourceURI);
      return null;

    });

    this.textureCache[cacheKey] = promise;

    return promise;

  }

  /**
   * Asynchronously assigns a texture to the given material parameters.
   * @param {Object} materialParams
   * @param {string} mapName
   * @param {Object} mapDef
   * @return {Promise<Texture>}
   */
  assignTexture(materialParams, mapName, mapDef) {

    const parser = this;

    return this.getDependency('texture', mapDef.index).then(function (texture) {

      // Materials sample aoMap from UV set 1 and other maps from UV set 0 - this can't be configured
      // However, we will copy UV set 0 to UV set 1 on demand for aoMap
      if (mapDef.texCoord !== undefined && mapDef.texCoord != 0 && !(mapName === 'aoMap' && mapDef.texCoord == 1)) {

        console.warn('THREE.GLTFLoader: Custom UV set ' + mapDef.texCoord + ' for texture ' + mapName + ' not yet supported.');

      }

      if (parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]) {

        const transform = mapDef.extensions !== undefined ? mapDef.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM] : undefined;

        if (transform) {

          const gltfReference = parser.associations.get(texture);
          texture = parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM].extendTexture(texture, transform);
          parser.associations.set(texture, gltfReference);

        }

      }

      materialParams[mapName] = texture;

      return texture;

    });

  }

  /**
   * Assigns final material to a Mesh, Line, or Points instance. The instance
   * already has a material (generated from the glTF material options alone)
   * but reuse of the same glTF material may require multiple threejs materials
   * to accommodate different primitive types, defines, etc. New materials will
   * be created if necessary, and reused from a cache.
   * @param  {Object3D} mesh Mesh, Line, or Points instance.
   */
  assignFinalMaterial(mesh) {

    const geometry = mesh.geometry;
    let material = mesh.material;

    const useDerivativeTangents = geometry.attributes.tangent === undefined;
    const useVertexColors = geometry.attributes.color !== undefined;
    const useFlatShading = geometry.attributes.normal === undefined;

    if (mesh.isPoints) {

      const cacheKey = 'PointsMaterial:' + material.uuid;

      let pointsMaterial = this.cache.get(cacheKey);

      if (!pointsMaterial) {

        pointsMaterial = new PointsMaterial();
        Material.prototype.copy.call(pointsMaterial, material);
        pointsMaterial.color.copy(material.color);
        pointsMaterial.map = material.map;
        pointsMaterial.sizeAttenuation = false; // glTF spec says points should be 1px

        this.cache.add(cacheKey, pointsMaterial);

      }

      material = pointsMaterial;

    } else if (mesh.isLine) {

      const cacheKey = 'LineBasicMaterial:' + material.uuid;

      let lineMaterial = this.cache.get(cacheKey);

      if (!lineMaterial) {

        lineMaterial = new LineBasicMaterial();
        Material.prototype.copy.call(lineMaterial, material);
        lineMaterial.color.copy(material.color);

        this.cache.add(cacheKey, lineMaterial);

      }

      material = lineMaterial;

    }

    // Clone the material if it will be modified
    if (useDerivativeTangents || useVertexColors || useFlatShading) {

      let cacheKey = 'ClonedMaterial:' + material.uuid + ':';

      if (material.isGLTFSpecularGlossinessMaterial) cacheKey += 'specular-glossiness:';
      if (useDerivativeTangents) cacheKey += 'derivative-tangents:';
      if (useVertexColors) cacheKey += 'vertex-colors:';
      if (useFlatShading) cacheKey += 'flat-shading:';

      let cachedMaterial = this.cache.get(cacheKey);

      if (!cachedMaterial) {

        cachedMaterial = material.clone();

        if (useVertexColors) cachedMaterial.vertexColors = true;
        if (useFlatShading) cachedMaterial.flatShading = true;

        if (useDerivativeTangents) {

          // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
          if (cachedMaterial.normalScale) cachedMaterial.normalScale.y *= -1;
          if (cachedMaterial.clearcoatNormalScale) cachedMaterial.clearcoatNormalScale.y *= -1;

        }

        this.cache.add(cacheKey, cachedMaterial);

        this.associations.set(cachedMaterial, this.associations.get(material));

      }

      material = cachedMaterial;

    }

    // workarounds for mesh and geometry

    if (material.aoMap && geometry.attributes.uv2 === undefined && geometry.attributes.uv !== undefined) {

      geometry.setAttribute('uv2', geometry.attributes.uv);

    }

    mesh.material = material;

  }

  getMaterialType( /* materialIndex */) {

    return MeshStandardMaterial;

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
   * @param {number} materialIndex
   * @return {Promise<Material>}
   */
  loadMaterial(materialIndex) {

    const parser = this;
    const json = this.json;
    const extensions = this.extensions;
    const materialDef = json.materials[materialIndex];

    let materialType;
    const materialParams = {};
    const materialExtensions = materialDef.extensions || {};

    const pending = [];

    if (materialExtensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS]) {

      const sgExtension = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS];
      materialType = sgExtension.getMaterialType();
      pending.push(sgExtension.extendParams(materialParams, materialDef, parser));

    } else if (materialExtensions[EXTENSIONS.KHR_MATERIALS_UNLIT]) {

      const kmuExtension = extensions[EXTENSIONS.KHR_MATERIALS_UNLIT];
      materialType = kmuExtension.getMaterialType();
      pending.push(kmuExtension.extendParams(materialParams, materialDef, parser));

    } else {

      // Specification:
      // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material

      const metallicRoughness = materialDef.pbrMetallicRoughness || {};

      materialParams.color = new Color(1.0, 1.0, 1.0);
      materialParams.opacity = 1.0;

      if (Array.isArray(metallicRoughness.baseColorFactor)) {

        const array = metallicRoughness.baseColorFactor;

        materialParams.color.fromArray(array);
        materialParams.opacity = array[3];

      }

      if (metallicRoughness.baseColorTexture !== undefined) {

        pending.push(parser.assignTexture(materialParams, 'map', metallicRoughness.baseColorTexture));

      }

      materialParams.metalness = metallicRoughness.metallicFactor !== undefined ? metallicRoughness.metallicFactor : 1.0;
      materialParams.roughness = metallicRoughness.roughnessFactor !== undefined ? metallicRoughness.roughnessFactor : 1.0;

      if (metallicRoughness.metallicRoughnessTexture !== undefined) {

        pending.push(parser.assignTexture(materialParams, 'metalnessMap', metallicRoughness.metallicRoughnessTexture));
        pending.push(parser.assignTexture(materialParams, 'roughnessMap', metallicRoughness.metallicRoughnessTexture));

      }

      materialType = this._invokeOne(function (ext) {

        return ext.getMaterialType && ext.getMaterialType(materialIndex);

      });

      pending.push(Promise.all(this._invokeAll(function (ext) {

        return ext.extendMaterialParams && ext.extendMaterialParams(materialIndex, materialParams);

      })));

    }

    if (materialDef.doubleSided === true) {

      materialParams.side = DoubleSide;

    }

    const alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;

    if (alphaMode === ALPHA_MODES.BLEND) {

      materialParams.transparent = true;

      // See: https://github.com/mrdoob/three.js/issues/17706
      materialParams.depthWrite = false;

    } else {

      materialParams.format = RGBFormat;
      materialParams.transparent = false;

      if (alphaMode === ALPHA_MODES.MASK) {

        materialParams.alphaTest = materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;

      }

    }

    if (materialDef.normalTexture !== undefined && materialType !== MeshBasicMaterial) {

      pending.push(parser.assignTexture(materialParams, 'normalMap', materialDef.normalTexture));

      materialParams.normalScale = new Vector2(1, 1);

      if (materialDef.normalTexture.scale !== undefined) {

        const scale = materialDef.normalTexture.scale;

        materialParams.normalScale.set(scale, scale);

      }

    }

    if (materialDef.occlusionTexture !== undefined && materialType !== MeshBasicMaterial) {

      pending.push(parser.assignTexture(materialParams, 'aoMap', materialDef.occlusionTexture));

      if (materialDef.occlusionTexture.strength !== undefined) {

        materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;

      }

    }

    if (materialDef.emissiveFactor !== undefined && materialType !== MeshBasicMaterial) {

      materialParams.emissive = new Color().fromArray(materialDef.emissiveFactor);

    }

    if (materialDef.emissiveTexture !== undefined && materialType !== MeshBasicMaterial) {

      pending.push(parser.assignTexture(materialParams, 'emissiveMap', materialDef.emissiveTexture));

    }

    return Promise.all(pending).then(function () {

      let material;

      if (materialType === GLTFMeshStandardSGMaterial) {

        material = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS].createMaterial(materialParams);

      } else {

        material = new materialType(materialParams);

      }

      if (materialDef.name) material.name = materialDef.name;

      // baseColorTexture, emissiveTexture, and specularGlossinessTexture use sRGB encoding.
      if (material.map) material.map.encoding = sRGBEncoding;
      if (material.emissiveMap) material.emissiveMap.encoding = sRGBEncoding;

      assignExtrasToUserData(material, materialDef);

      parser.associations.set(material, {materials: materialIndex});

      if (materialDef.extensions) addUnknownExtensionsToUserData(extensions, material, materialDef);

      return material;

    });

  }

  /** When Object3D instances are targeted by animation, they need unique names. */
  createUniqueName(originalName) {

    const sanitizedName = PropertyBinding.sanitizeNodeName(originalName || '');

    let name = sanitizedName;

    for (let i = 1; this.nodeNamesUsed[name]; ++i) {

      name = sanitizedName + '_' + i;

    }

    this.nodeNamesUsed[name] = true;

    return name;

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
   *
   * Creates BufferGeometries from primitives.
   *
   * @param {Array<GLTF.Primitive>} primitives
   * @return {Promise<Array<BufferGeometry>>}
   */
  loadGeometries(primitives) {

    const parser = this;
    const extensions = this.extensions;
    const cache = this.primitiveCache;

    function createDracoPrimitive(primitive) {

      return extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
        .decodePrimitive(primitive, parser)
        .then(function (geometry) {

          return addPrimitiveAttributes(geometry, primitive, parser);

        });

    }

    const pending = [];

    for (let i = 0, il = primitives.length; i < il; i++) {

      const primitive = primitives[i];
      const cacheKey = createPrimitiveKey(primitive);

      // See if we've already created this geometry
      const cached = cache[cacheKey];

      if (cached) {

        // Use the cached geometry if it exists
        pending.push(cached.promise);

      } else {

        let geometryPromise;

        if (primitive.extensions && primitive.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]) {

          // Use DRACO geometry if available
          geometryPromise = createDracoPrimitive(primitive);

        } else {

          // Otherwise create a new geometry
          geometryPromise = addPrimitiveAttributes(new BufferGeometry(), primitive, parser);

        }

        // Cache this geometry
        cache[cacheKey] = {primitive: primitive, promise: geometryPromise};

        pending.push(geometryPromise);

      }

    }

    return Promise.all(pending);

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
   * @param {number} meshIndex
   * @return {Promise<Group|Mesh|SkinnedMesh>}
   */
  loadMesh(meshIndex) {

    const parser = this;
    const json = this.json;
    const extensions = this.extensions;

    const meshDef = json.meshes[meshIndex];
    const primitives = meshDef.primitives;

    const pending = [];

    for (let i = 0, il = primitives.length; i < il; i++) {

      const material = primitives[i].material === undefined
        ? createDefaultMaterial(this.cache)
        : this.getDependency('material', primitives[i].material);

      pending.push(material);

    }

    pending.push(parser.loadGeometries(primitives));

    return Promise.all(pending).then(function (results) {

      const materials = results.slice(0, results.length - 1);
      const geometries = results[results.length - 1];

      const meshes = [];

      for (let i = 0, il = geometries.length; i < il; i++) {

        const geometry = geometries[i];
        const primitive = primitives[i];

        // 1. create Mesh

        let mesh;

        const material = materials[i];

        if (primitive.mode === WEBGL_CONSTANTS.TRIANGLES ||
          primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ||
          primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ||
          primitive.mode === undefined) {

          // .isSkinnedMesh isn't in glTF spec. See ._markDefs()
          mesh = meshDef.isSkinnedMesh === true
            ? new SkinnedMesh(geometry, material)
            : new Mesh(geometry, material);

          if (mesh.isSkinnedMesh === true && !mesh.geometry.attributes.skinWeight.normalized) {

            // we normalize floating point skin weight array to fix malformed assets (see #15319)
            // it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
            mesh.normalizeSkinWeights();

          }

          if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP) {

            mesh.geometry = toTrianglesDrawMode(mesh.geometry, TriangleStripDrawMode);

          } else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {

            mesh.geometry = toTrianglesDrawMode(mesh.geometry, TriangleFanDrawMode);

          }

        } else if (primitive.mode === WEBGL_CONSTANTS.LINES) {

          mesh = new LineSegments(geometry, material);

        } else if (primitive.mode === WEBGL_CONSTANTS.LINE_STRIP) {

          mesh = new Line(geometry, material);

        } else if (primitive.mode === WEBGL_CONSTANTS.LINE_LOOP) {

          mesh = new LineLoop(geometry, material);

        } else if (primitive.mode === WEBGL_CONSTANTS.POINTS) {

          mesh = new Points(geometry, material);

        } else {

          throw new Error('THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode);

        }

        if (Object.keys(mesh.geometry.morphAttributes).length > 0) {

          updateMorphTargets(mesh, meshDef);

        }

        mesh.name = parser.createUniqueName(meshDef.name || ('mesh_' + meshIndex));

        assignExtrasToUserData(mesh, meshDef);

        if (primitive.extensions) addUnknownExtensionsToUserData(extensions, mesh, primitive);

        parser.assignFinalMaterial(mesh);

        meshes.push(mesh);

      }

      for (let i = 0, il = meshes.length; i < il; i++) {

        parser.associations.set(meshes[i], {
          meshes: meshIndex,
          primitives: i
        });

      }

      if (meshes.length === 1) {

        return meshes[0];

      }

      const group = new Group();

      parser.associations.set(group, {meshes: meshIndex});

      for (let i = 0, il = meshes.length; i < il; i++) {

        group.add(meshes[i]);

      }

      return group;

    });

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
   * @param {number} cameraIndex
   * @return {Promise<THREE.Camera>}
   */
  loadCamera(cameraIndex) {

    let camera;
    const cameraDef = this.json.cameras[cameraIndex];
    const params = cameraDef[cameraDef.type];

    if (!params) {

      console.warn('THREE.GLTFLoader: Missing camera parameters.');
      return;

    }

    if (cameraDef.type === 'perspective') {

      camera = new PerspectiveCamera(MathUtils.radToDeg(params.yfov), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6);

    } else if (cameraDef.type === 'orthographic') {

      camera = new OrthographicCamera(-params.xmag, params.xmag, params.ymag, -params.ymag, params.znear, params.zfar);

    }

    if (cameraDef.name) camera.name = this.createUniqueName(cameraDef.name);

    assignExtrasToUserData(camera, cameraDef);

    return Promise.resolve(camera);

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
   * @param {number} skinIndex
   * @return {Promise<Object>}
   */
  loadSkin(skinIndex) {

    const skinDef = this.json.skins[skinIndex];

    const skinEntry = {joints: skinDef.joints};

    if (skinDef.inverseBindMatrices === undefined) {

      return Promise.resolve(skinEntry);

    }

    return this.getDependency('accessor', skinDef.inverseBindMatrices).then(function (accessor) {

      skinEntry.inverseBindMatrices = accessor;

      return skinEntry;

    });

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
   * @param {number} animationIndex
   * @return {Promise<AnimationClip>}
   */
  loadAnimation(animationIndex) {

    const json = this.json;

    const animationDef = json.animations[animationIndex];

    const pendingNodes = [];
    const pendingInputAccessors = [];
    const pendingOutputAccessors = [];
    const pendingSamplers = [];
    const pendingTargets = [];

    for (let i = 0, il = animationDef.channels.length; i < il; i++) {

      const channel = animationDef.channels[i];
      const sampler = animationDef.samplers[channel.sampler];
      const target = channel.target;
      const name = target.node !== undefined ? target.node : target.id; // NOTE: target.id is deprecated.
      const input = animationDef.parameters !== undefined ? animationDef.parameters[sampler.input] : sampler.input;
      const output = animationDef.parameters !== undefined ? animationDef.parameters[sampler.output] : sampler.output;

      pendingNodes.push(this.getDependency('node', name));
      pendingInputAccessors.push(this.getDependency('accessor', input));
      pendingOutputAccessors.push(this.getDependency('accessor', output));
      pendingSamplers.push(sampler);
      pendingTargets.push(target);

    }

    return Promise.all([

      Promise.all(pendingNodes),
      Promise.all(pendingInputAccessors),
      Promise.all(pendingOutputAccessors),
      Promise.all(pendingSamplers),
      Promise.all(pendingTargets)

    ]).then(function (dependencies) {

      const nodes = dependencies[0];
      const inputAccessors = dependencies[1];
      const outputAccessors = dependencies[2];
      const samplers = dependencies[3];
      const targets = dependencies[4];

      const tracks = [];

      for (let i = 0, il = nodes.length; i < il; i++) {

        const node = nodes[i];
        const inputAccessor = inputAccessors[i];
        const outputAccessor = outputAccessors[i];
        const sampler = samplers[i];
        const target = targets[i];

        if (node === undefined) continue;

        node.updateMatrix();
        node.matrixAutoUpdate = true;

        let TypedKeyframeTrack;

        switch (PATH_PROPERTIES[target.path]) {

          case PATH_PROPERTIES.weights:

            TypedKeyframeTrack = NumberKeyframeTrack;
            break;

          case PATH_PROPERTIES.rotation:

            TypedKeyframeTrack = QuaternionKeyframeTrack;
            break;

          case PATH_PROPERTIES.position:
          case PATH_PROPERTIES.scale:
          default:

            TypedKeyframeTrack = VectorKeyframeTrack;
            break;

        }

        const targetName = node.name ? node.name : node.uuid;

        const interpolation = sampler.interpolation !== undefined ? INTERPOLATION[sampler.interpolation] : InterpolateLinear;

        const targetNames = [];

        if (PATH_PROPERTIES[target.path] === PATH_PROPERTIES.weights) {

          node.traverse(function (object) {

            if (object.morphTargetInfluences) {

              targetNames.push(object.name ? object.name : object.uuid);

            }

          });

        } else {

          targetNames.push(targetName);

        }

        let outputArray = outputAccessor.array;

        if (outputAccessor.normalized) {

          const scale = getNormalizedComponentScale(outputArray.constructor);
          const scaled = new Float32Array(outputArray.length);

          for (let j = 0, jl = outputArray.length; j < jl; j++) {

            scaled[j] = outputArray[j] * scale;

          }

          outputArray = scaled;

        }

        for (let j = 0, jl = targetNames.length; j < jl; j++) {

          const track = new TypedKeyframeTrack(
            targetNames[j] + '.' + PATH_PROPERTIES[target.path],
            inputAccessor.array,
            outputArray,
            interpolation
          );

          // Override interpolation with custom factory method.
          if (sampler.interpolation === 'CUBICSPLINE') {

            track.createInterpolant = function InterpolantFactoryMethodGLTFCubicSpline(result) {

              // A CUBICSPLINE keyframe in glTF has three output values for each input value,
              // representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
              // must be divided by three to get the interpolant's sampleSize argument.

              const interpolantType = (this instanceof QuaternionKeyframeTrack) ? GLTFCubicSplineQuaternionInterpolant : GLTFCubicSplineInterpolant;

              return new interpolantType(this.times, this.values, this.getValueSize() / 3, result);

            };

            // Mark as CUBICSPLINE. `track.getInterpolation()` doesn't support custom interpolants.
            track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;

          }

          tracks.push(track);

        }

      }

      const name = animationDef.name ? animationDef.name : 'animation_' + animationIndex;

      return new AnimationClip(name, undefined, tracks);

    });

  }

  createNodeMesh(nodeIndex) {

    const json = this.json;
    const parser = this;
    const nodeDef = json.nodes[nodeIndex];

    if (nodeDef.mesh === undefined) return null;

    return parser.getDependency('mesh', nodeDef.mesh).then(function (mesh) {

      const node = parser._getNodeRef(parser.meshCache, nodeDef.mesh, mesh);

      // if weights are provided on the node, override weights on the mesh.
      if (nodeDef.weights !== undefined) {

        node.traverse(function (o) {

          if (!o.isMesh) return;

          for (let i = 0, il = nodeDef.weights.length; i < il; i++) {

            o.morphTargetInfluences[i] = nodeDef.weights[i];

          }

        });

      }

      return node;

    });

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
   * @param {number} nodeIndex
   * @return {Promise<Object3D>}
   */
  loadNode(nodeIndex) {

    const json = this.json;
    const extensions = this.extensions;
    const parser = this;

    const nodeDef = json.nodes[nodeIndex];

    // reserve node's name before its dependencies, so the root has the intended name.
    const nodeName = nodeDef.name ? parser.createUniqueName(nodeDef.name) : '';

    return (function () {

      const pending = [];

      const meshPromise = parser._invokeOne(function (ext) {

        return ext.createNodeMesh && ext.createNodeMesh(nodeIndex);

      });

      if (meshPromise) {

        pending.push(meshPromise);

      }

      if (nodeDef.camera !== undefined) {

        pending.push(parser.getDependency('camera', nodeDef.camera).then(function (camera) {

          return parser._getNodeRef(parser.cameraCache, nodeDef.camera, camera);

        }));

      }

      parser._invokeAll(function (ext) {

        return ext.createNodeAttachment && ext.createNodeAttachment(nodeIndex);

      }).forEach(function (promise) {

        pending.push(promise);

      });

      return Promise.all(pending);

    }()).then(function (objects) {

      let node;

      // .isBone isn't in glTF spec. See ._markDefs
      if (nodeDef.isBone === true) {

        node = new Bone();

      } else if (objects.length > 1) {

        node = new Group();

      } else if (objects.length === 1) {

        node = objects[0];

      } else {

        node = new Object3D();

      }

      if (node !== objects[0]) {

        for (let i = 0, il = objects.length; i < il; i++) {

          node.add(objects[i]);

        }

      }

      if (nodeDef.name) {

        node.userData.name = nodeDef.name;
        node.name = nodeName;

      }

      assignExtrasToUserData(node, nodeDef);

      if (nodeDef.extensions) addUnknownExtensionsToUserData(extensions, node, nodeDef);

      if (nodeDef.matrix !== undefined) {

        const matrix = new Matrix4();
        matrix.fromArray(nodeDef.matrix);
        node.applyMatrix4(matrix);

      } else {

        if (nodeDef.translation !== undefined) {

          node.position.fromArray(nodeDef.translation);

        }

        if (nodeDef.rotation !== undefined) {

          node.quaternion.fromArray(nodeDef.rotation);

        }

        if (nodeDef.scale !== undefined) {

          node.scale.fromArray(nodeDef.scale);

        }

      }

      if (!parser.associations.has(node)) {

        parser.associations.set(node, {});

      }

      parser.associations.get(node).nodes = nodeIndex;

      return node;

    });

  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
   * @param {number} sceneIndex
   * @return {Promise<Group>}
   */
  loadScene(sceneIndex) {

    const json = this.json;
    const extensions = this.extensions;
    const sceneDef = this.json.scenes[sceneIndex];
    const parser = this;

    // Loader returns Group, not Scene.
    // See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172
    const scene = new Group();
    if (sceneDef.name) scene.name = parser.createUniqueName(sceneDef.name);

    assignExtrasToUserData(scene, sceneDef);

    if (sceneDef.extensions) addUnknownExtensionsToUserData(extensions, scene, sceneDef);

    const nodeIds = sceneDef.nodes || [];

    const pending = [];

    for (let i = 0, il = nodeIds.length; i < il; i++) {

      pending.push(buildNodeHierarchy(nodeIds[i], scene, json, parser));

    }

    return Promise.all(pending).then(function () {

      // Removes dangling associations, associations that reference a node that
      // didn't make it into the scene.
      const reduceAssociations = (node) => {

        const reducedAssociations = new Map();

        for (const [key, value] of parser.associations) {

          if (key instanceof Material || key instanceof Texture) {

            reducedAssociations.set(key, value);

          }

        }

        node.traverse((node) => {

          const mappings = parser.associations.get(node);

          if (mappings != null) {

            reducedAssociations.set(node, mappings);

          }

        });

        return reducedAssociations;

      };

      parser.associations = reduceAssociations(scene);

      return scene;

    });

  }

}

function buildNodeHierarchy(nodeId, parentObject, json, parser) {

  const nodeDef = json.nodes[nodeId];

  return parser.getDependency('node', nodeId).then(function (node) {

    if (nodeDef.skin === undefined) return node;

    // build skeleton here as well

    let skinEntry;

    return parser.getDependency('skin', nodeDef.skin).then(function (skin) {

      skinEntry = skin;

      const pendingJoints = [];

      for (let i = 0, il = skinEntry.joints.length; i < il; i++) {

        pendingJoints.push(parser.getDependency('node', skinEntry.joints[i]));

      }

      return Promise.all(pendingJoints);

    }).then(function (jointNodes) {

      node.traverse(function (mesh) {

        if (!mesh.isMesh) return;

        const bones = [];
        const boneInverses = [];

        for (let j = 0, jl = jointNodes.length; j < jl; j++) {

          const jointNode = jointNodes[j];

          if (jointNode) {

            bones.push(jointNode);

            const mat = new Matrix4();

            if (skinEntry.inverseBindMatrices !== undefined) {

              mat.fromArray(skinEntry.inverseBindMatrices.array, j * 16);

            }

            boneInverses.push(mat);

          } else {

            console.warn('THREE.GLTFLoader: Joint "%s" could not be found.', skinEntry.joints[j]);

          }

        }

        mesh.bind(new Skeleton(bones, boneInverses), mesh.matrixWorld);

      });

      return node;

    });

  }).then(function (node) {

    // build node hierachy

    parentObject.add(node);

    const pending = [];

    if (nodeDef.children) {

      const children = nodeDef.children;

      for (let i = 0, il = children.length; i < il; i++) {

        const child = children[i];
        pending.push(buildNodeHierarchy(child, node, json, parser));

      }

    }

    return Promise.all(pending);

  });

}

/**
 * @param {BufferGeometry} geometry
 * @param {GLTF.Primitive} primitiveDef
 * @param {GLTFParser} parser
 */
function computeBounds(geometry, primitiveDef, parser) {

  const attributes = primitiveDef.attributes;

  const box = new Box3();

  if (attributes.POSITION !== undefined) {

    const accessor = parser.json.accessors[attributes.POSITION];

    const min = accessor.min;
    const max = accessor.max;

    // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

    if (min !== undefined && max !== undefined) {

      box.set(
        new Vector3(min[0], min[1], min[2]),
        new Vector3(max[0], max[1], max[2])
      );

      if (accessor.normalized) {

        const boxScale = getNormalizedComponentScale(WEBGL_COMPONENT_TYPES[accessor.componentType]);
        box.min.multiplyScalar(boxScale);
        box.max.multiplyScalar(boxScale);

      }

    } else {

      console.warn('THREE.GLTFLoader: Missing min/max properties for accessor POSITION.');

      return;

    }

  } else {

    return;

  }

  const targets = primitiveDef.targets;

  if (targets !== undefined) {

    const maxDisplacement = new Vector3();
    const vector = new Vector3();

    for (let i = 0, il = targets.length; i < il; i++) {

      const target = targets[i];

      if (target.POSITION !== undefined) {

        const accessor = parser.json.accessors[target.POSITION];
        const min = accessor.min;
        const max = accessor.max;

        // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

        if (min !== undefined && max !== undefined) {

          // we need to get max of absolute components because target weight is [-1,1]
          vector.setX(Math.max(Math.abs(min[0]), Math.abs(max[0])));
          vector.setY(Math.max(Math.abs(min[1]), Math.abs(max[1])));
          vector.setZ(Math.max(Math.abs(min[2]), Math.abs(max[2])));


          if (accessor.normalized) {

            const boxScale = getNormalizedComponentScale(WEBGL_COMPONENT_TYPES[accessor.componentType]);
            vector.multiplyScalar(boxScale);

          }

          // Note: this assumes that the sum of all weights is at most 1. This isn't quite correct - it's more conservative
          // to assume that each target can have a max weight of 1. However, for some use cases - notably, when morph targets
          // are used to implement key-frame animations and as such only two are active at a time - this results in very large
          // boxes. So for now we make a box that's sometimes a touch too small but is hopefully mostly of reasonable size.
          maxDisplacement.max(vector);

        } else {

          console.warn('THREE.GLTFLoader: Missing min/max properties for accessor POSITION.');

        }

      }

    }

    // As per comment above this box isn't conservative, but has a reasonable size for a very large number of morph targets.
    box.expandByVector(maxDisplacement);

  }

  geometry.boundingBox = box;

  const sphere = new Sphere();

  box.getCenter(sphere.center);
  sphere.radius = box.min.distanceTo(box.max) / 2;

  geometry.boundingSphere = sphere;

}

/**
 * @param {BufferGeometry} geometry
 * @param {GLTF.Primitive} primitiveDef
 * @param {GLTFParser} parser
 * @return {Promise<BufferGeometry>}
 */
function addPrimitiveAttributes(geometry, primitiveDef, parser) {

  const attributes = primitiveDef.attributes;

  const pending = [];

  function assignAttributeAccessor(accessorIndex, attributeName) {

    return parser.getDependency('accessor', accessorIndex)
      .then(function (accessor) {

        geometry.setAttribute(attributeName, accessor);

      });

  }

  for (const gltfAttributeName in attributes) {

    const threeAttributeName = ATTRIBUTES[gltfAttributeName] || gltfAttributeName.toLowerCase();

    // Skip attributes already provided by e.g. Draco extension.
    if (threeAttributeName in geometry.attributes) continue;

    pending.push(assignAttributeAccessor(attributes[gltfAttributeName], threeAttributeName));

  }

  if (primitiveDef.indices !== undefined && !geometry.index) {

    const accessor = parser.getDependency('accessor', primitiveDef.indices).then(function (accessor) {

      geometry.setIndex(accessor);

    });

    pending.push(accessor);

  }

  assignExtrasToUserData(geometry, primitiveDef);

  computeBounds(geometry, primitiveDef, parser);

  return Promise.all(pending).then(function () {

    return primitiveDef.targets !== undefined
      ? addMorphTargets(geometry, primitiveDef.targets, parser)
      : geometry;

  });

}

/**
 * @param {BufferGeometry} geometry
 * @param {Number} drawMode
 * @return {BufferGeometry}
 */
function toTrianglesDrawMode(geometry, drawMode) {

  let index = geometry.getIndex();

  // generate index if not present

  if (index === null) {

    const indices = [];

    const position = geometry.getAttribute('position');

    if (position !== undefined) {

      for (let i = 0; i < position.count; i++) {

        indices.push(i);

      }

      geometry.setIndex(indices);
      index = geometry.getIndex();

    } else {

      console.error('THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible.');
      return geometry;

    }

  }

  //

  const numberOfTriangles = index.count - 2;
  const newIndices = [];

  if (drawMode === TriangleFanDrawMode) {

    // gl.TRIANGLE_FAN

    for (let i = 1; i <= numberOfTriangles; i++) {

      newIndices.push(index.getX(0));
      newIndices.push(index.getX(i));
      newIndices.push(index.getX(i + 1));

    }

  } else {

    // gl.TRIANGLE_STRIP

    for (let i = 0; i < numberOfTriangles; i++) {

      if (i % 2 === 0) {

        newIndices.push(index.getX(i));
        newIndices.push(index.getX(i + 1));
        newIndices.push(index.getX(i + 2));


      } else {

        newIndices.push(index.getX(i + 2));
        newIndices.push(index.getX(i + 1));
        newIndices.push(index.getX(i));

      }

    }

  }

  if ((newIndices.length / 3) !== numberOfTriangles) {

    console.error('THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles.');

  }

  // build final geometry

  const newGeometry = geometry.clone();
  newGeometry.setIndex(newIndices);

  return newGeometry;

}

export {GLTFLoader};
